Achieved record Net Income, Retail Gross Margin and Adjusted EBITDA for full year 2017

Recorded $102.9 million in Adjusted EBITDA, $224.5 million in Retail Gross Margin, and $76.3 million in Net Income for the year ended 2017, representing year-over-year increases of 26%, 23%, and 16%, respectively

Recorded $28.9 million in Adjusted EBITDA, $66.2 million in Retail Gross Margin, and $47.5 million in Net Income for the fourth quarter, representing year-over-year increases of 17%, 13%, and 97%, respectively

Total RCE count increased 35% year-over-year to a record 1,042,000 as of December 31, 2017

Overall attrition of 4.3% for the year ended December 31, 2017

Closed three acquisitions in 2017

Two new acquisitions announced thus far in 2018 with a total of approximately 80,000 RCEs

“We are extremely proud to have delivered another year of record financial results despite unfavorable weather throughout the year,” said Nathan Kroeker, Spark Energy’s President and Chief Executive Officer. “We saw a mild summer and several severe weather events, including a devastating hurricane, but Spark was able to increase RCE count and improve both top and bottom line financial performance.

“During 2017, we completed three acquisitions, highlighted by the acquisition of Verde in July. We put a new credit facility in place and have added six new banks and a total of $185.0 million in commitments, which has since grown to $200.0 million in early 2018. In addition, we recently completed a $50.0 million follow-on offering of our Series A Preferred Stock. We launched a company-wide initiative to further integrate acquisitions and realize significant cost-to-serve synergies, including the early termination of the Verde earnout.

“As we move through 2018, we continue to strategically add customers and pursue additional opportunities to further streamline our business model. In March 2018, we agreed to acquire a small competitor in the Northeast as well as a book of customers from an affiliate of our sponsor. We expect both to be immediately accretive to Adjusted EBITDA. Our sponsor also agreed to reintegrate Retailco Services back into Spark, which will simplify our structure and result in immediate and substantial cash savings to the Company.”

“Finally, our Board of Directors has engaged Morgan Stanley as a financial advisor to explore strategic alternatives. We believe that our stock price has not reflected the strong growth in financial performance we have shown over the past three and a half years as a public company, and look forward to examining additional opportunities to unlock shareholder value.”

Summary Fourth Quarter 2017 Financial Results

For the quarter ended December 31, 2017, Spark reported Adjusted EBITDA of $28.9 million compared to Adjusted EBITDA of $24.8 million for the quarter ended December 31, 2016. This increase of $4.1 million is primarily attributable to additional volumes from the Verde and Perigee acquisitions.

For the quarter ended December 31, 2017, Spark reported Retail Gross Margin of $66.2 million compared to Retail Gross Margin of $58.8 million for the quarter ended December 31, 2016. This increase of $7.4 million is primarily attributable to the increased volumes of retail electricity following the Verde and Perigee acquisitions.

Net income for the quarter ended December 31, 2017, was $47.5 million compared to net income of $24.1 million for the quarter ended December 31, 2016, primarily due to higher retail gross margin and the revaluation of the Tax Receivable Agreement as a result of the new tax legislation.

Summary Full Year 2017 Financial Results

For the year ended December 31, 2017, Spark reported Adjusted EBITDA of $102.9 million compared to Adjusted EBITDA of $81.9 million for the year ended December 31, 2016. This increase of $21.0 million is primarily attributable to additional volumes from the Verde and Perigee acquisitions and a full year of the Provider and Major acquisitions, partially offset by milder-than-normal weather.

For the year ended December 31, 2017, Spark reported Retail Gross Margin of $224.5 million compared to Retail Gross Margin of $182.4 million for the year ended December 31, 2016. This increase of $42.1 million is primarily attributable to additional volumes from the Verde and Perigee acquisitions and a full year of the Provider and Major acquisitions, partially offset by milder-than-normal weather.

Net income for the year ended December 31, 2017, was $76.3 million compared to net income of $65.7 million for the year ended December 31, 2016, primarily due to higher volumes from the acquisitions and the revaluation of the Tax Receivable Agreement as a result of the new tax legislation.

Strategic Update

On March 1, 2018, Spark acquired a retail electric provider with approximately 29,000 RCEs serving electricity and natural gas customers in the Northeast and Midwest. The transaction is immediately accretive to 2018 earnings and requires minimal integration.

On March 7, 2018, Spark entered into an agreement with National Gas & Electric, LLC, ("NG&E"), an affiliate of Retailco, LLC, the Company's majority owner, for the acquisition of approximately 50,000 RCEs for approximately $12.5 million in cash. The transaction, which was reviewed and approved by a special committee made up of independent members of the Company's board of directors, is scheduled to close in April of this year.

On March 7, 2018, Spark agreed to reintegrate the employees and operations of Retailco Services, LLC ("Retailco"), which is wholly owned by W. Keith Maxwell III. Retailco was formed in 2015 to provide a variety of back office functions, including customer operations and information technology services, at a lower cost than Spark was realizing at the time. Retailco has been able to reduce the cost per customer over the past two years, and Spark expects to realize additional savings by reintegrating the two companies. This reintegration, which was reviewed and approved by a special committee of independent directors of the Company's board of directors, is scheduled to occur on April 1, 2018, and is expected to be accretive to 2018 earnings. Mr. Maxwell will receive no consideration for this transaction.

As previously announced, Spark terminated the Verde Energy earnout agreement on January 12, 2018. This transaction allowed Spark to begin integration of Verde's operations sooner than originally anticipated, which the Company believes should result in significant operational costs savings.

As mentioned above, the Board of Directors of Spark has retained Morgan Stanley as a financial advisor to explore strategic alternatives.

Outlook

Spark expects full year 2018 Adjusted EBITDA to be similar to that of 2017. The Company will continue to pursue accretive acquisitions, integrate recent acquisitions, drive operational performance improvements, and look to expand its geographic footprint.

Liquidity and Capital Resources

($ in thousands)

December 31, 2017

Cash and cash equivalents

$

29,419

Senior Credit Facility Availability (1)

12,501

Subordinated Debt Availability (2)

$

25,000

Total Liquidity

$

66,920

(1) Subject to Senior Credit Facility borrowing base and covenant restrictions.(2) The availability of the Subordinated Debt Facility provided by Spark’s founder is dependent on his financial position and liquidity. The Company may use the Subordinated Facility from time to time to enhance short-term liquidity but does not view the Subordinated Debt Facility as a material source of liquidity.

Since the beginning of 2018, Spark has increased the commitments on its credit facility by $15.0 million to $200.0 million. As previously mentioned, Spark also raised an additional $48.9 million in net proceeds in an offering of Series A Preferred Stock in January 2018.

Dividend

Spark’s Board of Directors declared quarterly dividends of $0.18125 per share of Class A common stock payable on March 16, 2018, and $0.546875 per share of Series A Preferred Stock payable on April 16, 2018. Investors are reminded that on June 16, 2017, Spark completed a two-for-one stock split by means of a stock dividend.

Conference Call and Webcast

Spark will host a conference call to discuss year end and fourth quarter 2017 results on Friday, March 9, 2018, at 10:00 AM Central Time (11:00 AM Eastern).

A live webcast of the conference call can be accessed from the Events & Presentations page of the Spark Energy Investor Relations website at http://ir.sparkenergy.com/events-and-presentations. An archived replay of the webcast will be available for twelve months following the live presentation.

About Spark Energy, Inc.

Spark Energy, Inc. is an established and growing independent retail energy services company founded in 1999 that provides residential and commercial customers in competitive markets across the United States with an alternative choice for their natural gas and electricity. Headquartered in Houston, Texas, Spark currently operates in 19 states and serves 94 utility territories. Spark offers its customers a variety of product and service choices, including stable and predictable energy costs and green product alternatives.

We use our website as a means of disclosing material non-public information and for complying with our disclosure obligations under Regulation FD. Investors should note that new materials, including press releases, updated investor presentations, and financial and other filings with the Securities and Exchange Commission are posted on the Spark Energy Investor Relations website at ir.sparkenergy.com. Investors are urged to monitor our website regularly for information and updates about the Company.

Cautionary Note Regarding Forward Looking Statements

This earnings release contains forward-looking statements that are subject to a number of risks and uncertainties, many of which are beyond our control. These forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”) and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) can be identified by the use of forward-looking terminology including “may,” “should,” “likely,” “will,” “believe,” “expect,” “anticipate,” “estimate,” “continue,” “plan,” “intend,” “projects,” or other similar words. All statements, other than statements of historical fact included in this earnings release, regarding strategy, future operations, financial position, estimated revenues and losses, projected costs, prospects, plans, objectives and beliefs of management are forward-looking statements. Forward-looking statements appear in a number of places in this earnings release and may include statements about business strategy and prospects for growth, customer acquisition costs, ability to pay cash dividends, cash flow generation and liquidity, availability of terms of capital, competition and government regulation and general economic conditions. Although we believe that the expectations reflected in such forward-looking statements are reasonable, we cannot give any assurance that such expectations will prove correct.

The forward-looking statements in this earnings release are subject to risks and uncertainties. Important factors that could cause actual results to materially differ from those projected in the forward-looking statements include, but are not limited to:

changes in commodity prices and the sufficiency of risk management and hedging policies;

extreme and unpredictable weather conditions, and the impact of hurricanes and other natural disasters;

federal, state and local regulation, including the industry's ability to address or adapt to potentially restrictive new regulations that may be enacted by the New York Public Service Commission;

whether our majority stockholder or its affiliates offer us acquisition opportunities on terms that are commercially acceptable to us;

ability to successfully identify and complete, and efficiently integrate acquisitions into our operations;

competition; and

the “Risk Factors” in our latest Annual Report on Form 10-K, and in our quarterly reports, other public filings and press releases.

You should review the Risk Factors and other factors noted throughout or incorporated by reference in this earnings release that could cause our actual results to differ materially from those contained in any forward-looking statement. All forward-looking statements speak only as of the date of this earnings release. Unless required by law, we disclaim any obligation to publicly update or revise these statements whether as a result of new information, future events or otherwise. It is not possible for us to predict all risks, nor can we assess the impact of all factors on the business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements.

SPARK ENERGY, INC.CONDENSED CONSOLIDATED BALANCE SHEETS AS OF DECEMBER 31, 2017 AND DECEMBER 31, 2016(in thousands)(unaudited)

December 31, 2017

December 31, 2016

Assets

Current assets:

Cash and cash equivalents

$

29,419

$

18,960

Accounts receivable, net of allowance for doubtful accounts of $4.0 million and $2.3 million asof December 31, 2017 and 2016, respectively

158,814

112,491

Accounts receivable—affiliates

3,661

2,624

Inventory

4,470

3,752

Fair value of derivative assets

31,191

8,344

Customer acquisition costs, net

22,123

18,834

Customer relationships, net

18,653

12,113

Prepaid assets

1,028

1,361

Deposits

7,701

7,329

Other current assets

19,678

12,175

Total current assets

296,738

197,983

Property and equipment, net

8,275

4,706

Fair value of derivative assets

3,309

3,083

Customer acquisition costs, net

6,949

6,134

Customer relationships, net

34,839

21,410

Deferred tax assets

24,185

54,109

Goodwill

120,154

79,147

Other assets

11,500

8,658

Total Assets

505,949

375,230

Liabilities, Series A Preferred Stock and Stockholders' Equity

Current liabilities:

Accounts payable

$

77,510

$

52,309

Accounts payable—affiliates

4,622

3,775

Accrued liabilities

33,679

36,619

Fair value of derivative liabilities

1,637

680

Current portion of Senior Credit Facility

7,500

51,287

Current payable pursuant to tax receivable agreement—affiliates

5,937

—

Current contingent consideration for acquisitions

4,024

11,827

Current portion of note payable

13,443

15,501

Convertible subordinated notes to affiliates

—

6,582

Other current liabilities

2,675

5,476

Total current liabilities

151,027

184,056

Long-term liabilities:

Fair value of derivative liabilities

492

68

Payable pursuant to tax receivable agreement—affiliates

26,355

49,886

Long-term portion of Senior Credit Facility

117,750

—

Subordinated debt—affiliate

—

5,000

Contingent consideration for acquisitions

626

10,826

Other long-term liabilities

172

1,658

Long-term portion of note payable

7,051

—

Total liabilities

$

303,473

$

251,494

Commitments and contingencies (Note 13)

Series A Preferred Stock, par value $0.01 per share, 20,000,000 shares authorized, 1,704,339 shares issued andoutstanding at December 31, 2017 and zero shares issued and outstanding at December 31, 2016

41,173

—

Stockholders' equity:

Common Stock (1) :

Class A common stock, par value $0.01 per share, 120,000,000 shares authorized, 13,235,082 issued and13,135,636 outstanding at December 31, 2017 and 12,993,118 issued and outstanding at December 31, 2016

Treasury stock, at cost, 99,446 shares at December 31, 2017 and zero shares at December 31, 2016

(2,011

)

—

Total stockholders' equity

36,248

30,330

Non-controlling interest in Spark HoldCo, LLC

125,055

93,406

Total equity

161,303

123,736

Total liabilities, Series A Preferred Stock and stockholders' equity

$

505,949

$

375,230

(1) Outstanding shares of common stock, additional paid-in capital and non-controlling interest reflect the two-for-one stock split, which took effect on June 16, 2017. See Note 4 "Equity" for further discussion.(2) See Note 4 "Equity" for disclosure of our variable interest entity in Spark HoldCo, LLC.

SPARK ENERGY, INC.CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME FOR THE YEARS ENDEDDECEMBER 31, 2017, 2016 and 2015(in thousands)(unaudited)

Year Ended December 31,

2017 (1)

2016 (2)

2015 (3)

Revenues:

Retail revenues

798,772

547,283

356,659

Net asset optimization (expense)/revenues (4)

(717

)

(586

)

1,494

Total Revenues

798,055

546,697

358,153

Operating Expenses:

Retail cost of revenues (5)

552,167

344,944

241,188

General and administrative (6)

101,127

84,964

61,682

Depreciation and amortization

42,341

32,788

25,378

Total Operating Expenses

695,635

462,696

328,248

Operating income

102,420

84,001

29,905

Other (expense)/income:

Interest expense

(11,134

)

(8,859

)

(2,280

)

Change in Tax Receivable Agreement liability

22,267

—

—

Interest and other income

256

957

324

Total other expenses

11,389

(7,902

)

(1,956

)

Income before income tax expense

113,809

76,099

27,949

Income tax expense

37,528

10,426

1,974

Net income

$

76,281

$

65,673

$

25,975

Less: Net income attributable to non-controlling interests

57,427

51,229

22,110

Net income attributable to Spark Energy, Inc. stockholders

$

18,854

$

14,444

$

3,865

Less: Dividend on Series A preferred stock

3,038

—

—

Net income attributable to stockholders of Class A common stock

$

15,816

$

14,444

$

3,865

Other comprehensive (loss) income, net of tax:

Currency translation (loss) gain

$

(59

)

$

41

$

—

Other comprehensive (loss) income

(59

)

41

—

Comprehensive income

$

76,222

$

65,714

$

25,975

Less: Comprehensive income attributable to non-controlling interests

57,390

51,259

22,110

Comprehensive income attributable to Spark Energy, Inc. stockholders

$

18,832

$

14,455

$

3,865

(1) Financial information includes results attributable to the acquisition of Perigee Energy, LLC by an affiliate on February 3, 2017. See Notes 2 and 3 "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions," respectively, for further discussion.(2) Financial information includes results attributable to the acquisition of Major Energy Companies from an affiliate on April 15, 2016. See Notes 2 and 3 "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions," respectively, for further discussion.(3) Financial information includes results attributable to the acquisition of Oasis Power Holdings LLC from an affiliate on May 12, 2015. See Notes 2 and 3 "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions," respectively, for further discussion.(4) Net asset optimization revenues includes asset optimization (expense)/revenues—affiliates of $1,334, $154 and $1,101 for the years ended December 31, 2017, 2016 and 2015, respectively, and asset optimization revenues—affiliates cost of revenues of $53, $1,633 and $11,285 for the years ended December 31, 2017, 2016 and 2015, respectively.(5) Retail cost of revenues includes retail cost of revenues—affiliates of $0, $9 and $17 for the years December 31, 2017, 2016 and 2015, respectively.(6) General and administrative includes general and administrative expense—affiliates of $24,700, $15,700 and $0 for the years ended December 31, 2017, 2016 and 2015, respectively.

SPARK ENERGY, INC.CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN EQUITY FOR THE YEARS ENDEDDECEMBER 31, 2017, 2016 and 2015(in thousands)(unaudited)

Issued Shares of Class A Common Stock (1)

Issued Shares of Class B Common Stock (1)

Treasury Stock

Class A Common Stock (1)

Class B Common Stock (1)

Treasury Stock

Accumulated Other Comprehensive Income (Loss)

Additional Paid-In Capital (1)

Retained Earnings (Deficit)

Total Stockholders' Equity

Non-controlling Interest (1)

Total Equity

Balance at 12/31/2014:

6,000

21,500

—

$

60

$

216

$

—

$

—

$

9,158

$

(775

)

$

8,659

$

15,458

$

24,117

Stock based compensation

—

—

—

—

—

—

—

2,165

—

2,165

—

2,165

Restricted stock unit vesting

238

—

—

2

—

—

—

185

—

187

—

187

Contribution from NuDevco

—

—

—

—

—

—

—

129

—

129

—

129

Consolidated net income (2)

—

—

—

—

—

—

—

—

3,865

3,865

22,110

25,975

Beneficial conversion feature

—

—

—

—

—

—

—

789

—

789

—

789

Distributions paid to Class B non-controlling unit holders

—

—

—

—

—

—

—

—

—

—

(15,587

)

(15,587

)

Dividends paid to Class A common shareholders

—

—

—

—

—

—

—

—

(4,456

)

(4,456

)

—

(4,456

)

Balance at 12/31/2015:

6,238

21,500

—

$

62

$

216

$

—

$

—

$

12,426

$

(1,366

)

$

11,338

$

21,981

$

33,319

Stock based compensation

—

—

—

—

—

—

2,270

—

2,270

—

2,270

Restricted stock unit vesting

305

—

—

4

—

—

—

1,058

—

1,062

—

1,062

Excess tax benefit related to restricted stock vesting

—

—

—

—

—

—

—

186

—

186

—

186

Consolidated net income (3)

—

—

—

—

—

—

—

—

14,444

14,444

51,229

65,673

Foreign currency translation adjustment for equity method investee

—

—

—

—

—

—

11

—

—

11

30

41

Beneficial conversion feature

—

—

—

—

—

—

—

243

—

243

—

243

Distributions paid to non-controlling unit holders

—

—

—

—

—

—

—

—

—

—

(34,931

)

(34,931

)

Net contribution of the Major Energy Companies

—

—

—

—

—

—

—

—

—

—

3,873

3,873

Dividends paid to Class A common stockholders

—

—

—

—

—

—

—

—

(8,367

)

(8,367

)

—

(8,367

)

Proceeds from disgorgement of stockholder short-swing profits

—

—

—

—

—

—

—

1,605

—

1,605

—

1,605

Tax impact from tax receivable agreement upon exchange of units of Spark HoldCo, LLC to shares of Class A Common Stock

—

—

—

—

—

—

—

4,768

—

4,768

—

4,768

Exchange of shares of Class B common stock to shares of Class A common stock

6,450

(6,450

)

—

64

(64

)

—

—

2,716

—

2,716

(2,716

)

—

Issuance of Class B Common Stock

—

5,400

—

—

54

—

—

—

—

54

53,940

53,994

Balance at 12/31/2016:

12,993

20,450

—

$

130

$

206

$

—

$

11

$

25,272

$

4,711

$

30,330

$

93,406

$

123,736

Stock based compensation

—

—

—

—

—

—

—

2,754

—

2,754

—

2,754

Restricted stock unit vesting

242

—

—

2

—

—

—

1,052

—

1,054

—

1,054

Consolidated net income (4)

—

—

—

—

—

—

—

—

18,854

18,854

57,427

76,281

Foreign currency translation adjustment for equity method investee

—

—

—

—

—

—

(22

)

—

—

(22

)

(37

)

(59

)

Distributions paid to non-controlling unit holders

—

—

—

—

—

—

—

—

—

—

(33,800

)

(33,800

)

Net contribution by NG&E

—

—

—

—

—

—

—

—

—

—

274

274

Dividends paid to Class A common stockholders

—

—

—

—

—

—

—

—

(9,519

)

(9,519

)

—

(9,519

)

Dividends to Preferred Stock

—

—

—

—

—

—

—

—

(3,038

)

(3,038

)

—

(3,038

)

Proceeds from disgorgement of stockholder short-swing profits

—

—

—

—

—

—

—

708

—

708

—

708

Tax receivable agreement liability true-up

—

—

—

—

—

—

—

(2,872

)

—

(2,872

)

—

(2,872

)

Conversion of Convertible Subordinated Notes to Class B Common Stock

—

1,035

—

—

10

—

—

—

—

10

7,785

7,795

Treasury Stock

—

—

(99

)

—

—

(2,011

)

—

—

—

(2,011

)

—

(2,011

)

Balance at 12/31/2017:

13,235

21,485

(99

)

$

132

$

216

$

(2,011

)

$

(11

)

$

26,914

$

11,008

$

36,248

$

125,055

$

161,303

(1) Outstanding shares of common stock, additional paid-in capital and non-controlling interest have been retrospectively adjusted to reflect the two-for-one stock split, which took effect on June 16, 2017. See Note 4 "Equity" for further discussion.

(2) Financial information includes results attributable to the acquisition of Oasis Power Holdings LLC from an affiliate on May 12, 2015. See Notes 2 and 3 "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions," respectively, for further discussion.

(3) Financial information includes results attributable to the acquisition of Major Energy Companies from an affiliate on April 15, 2016. See Notes 2 and 3 "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions," respectively, for further discussion.

(4) Financial information has been recast to include results attributable to the acquisition of Perigee Energy, LLC by an affiliate on February 3, 2017. See Notes 2 and 3 "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions," respectively, for further discussion.

(1) Financial information has been recast to include results attributable to the acquisition of Perigee Energy, LLC by an affiliate on February 3, 2017. See Notes 2 and 3 "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions," respectively, for further discussion.(2) Financial information has been recast to include results attributable to the acquisition of the Major Energy Companies from an affiliate on April 15, 2016. See Notes 2 and 3 "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions," respectively, for further discussion.(3) Financial information has been recast to include results attributable to the acquisition of Oasis Power Holdings LLC by an affiliate on May 12, 2015. See Note 2 "Basis of Presentation and Summary of Significant Accounting Policies" for further discussion.

We define “Adjusted EBITDA” as EBITDA less (i) customer acquisition costs incurred in the current period, (ii) net gain (loss) on derivative instruments, and (iii) net current period cash settlements on derivative instruments, plus (iv) non-cash compensation expense, and (v) other non-cash and non-recurring operating items. EBITDA is defined as net income (loss) before provision for income taxes, interest expense and depreciation and amortization. We deduct all current period customer acquisition costs (representing spending for organic customer acquisitions) in the Adjusted EBITDA calculation because such costs reflect a cash outlay in the period in which they are incurred, even though we capitalize such costs and amortize them over two years in accordance with our accounting policies. The deduction of current period customer acquisition costs is consistent with how we manage our business, but the comparability of Adjusted EBITDA between periods may be affected by varying levels of customer acquisition costs. For example, our Adjusted EBITDA is lower in years of customer growth reflecting larger customer acquisition spending. We do not deduct the cost of customer acquisitions through acquisitions of business or portfolios of customers in calculated Adjusted EBITDA. We deduct our net gains (losses) on derivative instruments, excluding current period cash settlements, from the Adjusted EBITDA calculation in order to remove the non-cash impact of net gains and losses on derivative instruments. We also deduct non-cash compensation expense as a result of restricted stock units that are issued under our long-term incentive plan.

We believe that the presentation of Adjusted EBITDA provides information useful to investors in assessing our liquidity and financial condition and results of operations and that Adjusted EBITDA is also useful to investors as a financial indicator of our ability to incur and service debt, pay dividends and fund capital expenditures. Adjusted EBITDA is a supplemental financial measure that management and external users of our condensed consolidated financial statements, such as industry analysts, investors, commercial banks and rating agencies, use to assess the following:

our operating performance as compared to other publicly traded companies in the retail energy industry, without regard to financing methods, capital structure or historical cost basis;

the ability of our assets to generate earnings sufficient to support our proposed cash dividends; and

We define retail gross margin as operating income (loss) plus (i) depreciation and amortization expenses and (ii) general and administrative expenses, less (i) net asset optimization revenues, (ii) net gains (losses) on non-trading derivative instruments, and (iii) net current period cash settlements on non-trading derivative instruments. Retail gross margin is included as a supplemental disclosure because it is a primary performance measure used by our management to determine the performance of our retail natural gas and electricity business by removing the impacts of our asset optimization activities and net non-cash income (loss) impact of our economic hedging activities. As an indicator of our retail energy business’ operating performance, retail gross margin should not be considered an alternative to, or more meaningful than, operating income (loss), its most directly comparable financial measure calculated and presented in accordance with GAAP.

The GAAP measures most directly comparable to Adjusted EBITDA are net income (loss) and net cash provided by operating activities. The GAAP measure most directly comparable to Retail Gross Margin is operating income (loss). Our non-GAAP financial measures of Adjusted EBITDA and Retail Gross Margin should not be considered as alternatives to net income (loss), net cash provided by operating activities, or operating income (loss). Adjusted EBITDA and Retail Gross Margin are not presentations made in accordance with GAAP and have important limitations as analytical tools. You should not consider Adjusted EBITDA or Retail Gross Margin in isolation or as a substitute for analysis of our results as reported under GAAP. Because Adjusted EBITDA and Retail Gross Margin exclude some, but not all, items that affect net income (loss) and net cash provided by operating activities, and are defined differently by different companies in our industry, our definition of Adjusted EBITDA and Retail Gross Margin may not be comparable to similarly titled measures of other companies.

Management compensates for the limitations of Adjusted EBITDA and Retail Gross Margin as analytical tools by reviewing the comparable GAAP measures, understanding the differences between the measures and incorporating these data points into management’s decision-making process.

The following tables present a reconciliation of Adjusted EBITDA to net income (loss) and net cash provided by operating activities for each of the periods indicated.

(1) Represents the change in the value of the Tax Receivable Agreement liability due to U.S. Tax Reform. (2) Includes $9.6 million and $1.1 million related to the change in fair value as the result of the revaluation of the Major Earnout liability at December 31, 2017 and 2016.

Year Ended December 31,

Quarter Ended December 31,

(in thousands)

2017

2016

2017

2016

Reconciliation of Adjusted EBITDA to netcash provided by operating activities:

Net cash provided by operating activities

$

63,912

$

67,793

$

88

$

6,150

Amortization of deferred financing costs

(1,035

)

(668

)

(285

)

(203

)

Allowance for doubtful accounts and baddebt expense

(6,550

)

(1,261

)

(3,114

)

(419

)

Interest expense

11,134

8,859

2,374

6,004

Income tax expense

37,528

10,426

32,263

3,574

Change in Tax Receivable Agreement liability (1)

(22,267

)

—

(22,267

)

—

Changes in operating working capital

Accounts receivable, prepaids, current assets

31,905

12,135

48,989

31,362

Inventory

718

542

(1,218

)

1,110

Accounts payable and accrued liabilities

(13,672

)

(17,653

)

(21,808

)

(23,507

)

Other

1,211

1,719

(6,141

)

745

Adjusted EBITDA

$

102,884

$

81,892

$

28,881

$

24,816

Cash Flow Data:

Cash flows provided by operating activity

$

63,912

$

67,793

$

88

$

6,150

Cash flows used in investing activity

(97,757

)

(36,344

)

(1,780

)

(2,169

)

Cash flows provided by (used in) financingactivity

44,304

(16,963

)

19,862

(1,928

)

(1) Represents the change in the value of the Tax Receivable Agreement liability due to U.S. Tax Reform.

The following table presents a reconciliation of Retail Gross Margin to operating income (loss) for each of the periods indicated.